As office equipment, a Multi Functional Printer (hereinafter referred to as MFP) having a copy function, a printer function and a facsimile function has been widely used.
The MFP realizes the copy function by performing image processing on image data read by scanner and outputting the result to a printer. In addition, the MFP realizes the printer function by receiving print data generated at a host side, rendering the print data, performing image processing on the print data and outputting the result to the printer.
The recent MFPs have a scanner function which uses a network as an I/F to transfer image data read by a scanner section via a network to a host, in addition to the functions mentioned above. A MFP having an HDD inside has a function for storing scanned image data in an HDD (hereinafter referred to as a document storing function) and is widely used for digitizing a document or the like on paper media.
<Arrangement of MFP>
Functions of each MFP including a document storing function will be described with reference to drawings. FIG. 1 is a block diagram showing an arrangement of an MFP.
A CPU (Central Processing Unit) 101 operates according to a program stored in ROM 102 and controls each section via an internal bus 113. A network I/F 106 is connected with the other devices on the network. In printing operation, the network I/F 106 controls process including a print request from a client PC on the network, outputting the print data, a data storage, and receiving the data to be stored. In scanning operation, the network I/F 106 controls for sending image data scanned by an MFP to a client PC on the network.
RAM 107 temporarily stores image data to be printed or scanned image data. In addition, the RAM 107 is a memory that functions as a main storage apparatus for storing program data of an executable program executed on the CPU 101 or an intermediate code or intermediate data whose program is being executed. ROM 102 is a read only memory for storing a control program for controlling over a device including an initial control such as booting of the MFP.
An HDD 104 is a sub storage apparatus for storing an execution program stored in the RAM 107, image data to be printed, and scanned image data for a short period or a long period by control of the CPU 101.
An operating section 103 has inputting means such as operation buttons and/or a touch panel corresponding to the operation intended by a user to operate the MFP. The operating section 103 has display means for displaying progress of internal processing or an internal status of the MFP and communicates user's operation to the CPU 101.
A scanner control section 105 and a printer control section 110 are control sections for driving and controlling a scanner 111, a printer 112, and image data transfer, respectively. The scanner 111 applies light on a manuscript placed on a manuscript glass platform from a light source and converts the reflected light into photoelectric by a photo acceptance unit to convert it into electronic image data.
In this description, a color type MFP and a monochrome type MFP are described by the same block diagrams. The scanner 111 in the color MFP is, however, adapted to generate image signals of RGB three channels and send them to the scanner control section 105 by using a CCD with three RGB color filters. The scanner 111 in the monochrome MFP is adapted to generate image signals of one channel and send it to the scanner control section 105 by using a CCD with a filter having a spectral sensitivity to a medium wavelength range.
The printer 112 includes a printer mechanism section for outputting a final printed output image. An electrophotographic printer converts image signals into laser modulation signals, applies light on a photosensitive drum, and develops toner on the photosensitive drum. And, this developed toner is transferred to a recording medium, and after the transferred toner is fixed, the recording medium is outputted as a print image. The printer 112 also has different configurations in the monochrome MFP and the color MFP. In the monochrome MFP, the printer 112 has only a developing section for a color of Bk (black). In the color printer, however, the printer 112 usually has a developing section for four colors of C (cyan), M (magenta), Y (yellow) and K (black), and prints an image by using toner of four colors of CMYK.
Usually, the printer 112 allows tone expressions by N bits for each pixel. Therefore, image data to be printed is represented by half tone for N bits in each color at an image processing section 108. The image processing section 108 also has functions of gamma correction processing and color converting processing. Each function of the image processing section 108 is realized by LSI.
An image compression/expansion section 109 is used for reducing data capacity when it temporarily stores scanned image data and/or image data to be printed. The monochrome MFP uses the JBIG compression technology appropriate for binary images. The color MFP uses the JPEG compression technology appropriate for color multilevel image.
<Function and Operational Flow of MFP>
A copy function, a scanner function via a network, and a document storage function in an MFP with the arrangement mentioned above and a processing flow of each function will be described below.
First, a processing function of the monochrome MFP will be described with reference to FIG. 2A.
The scanner 111 reads image data at a scanner reading section 201. A gamma processing section 202 and a binary processing section 203 mounted on the image processing section 108 are performed on image data read at the scanner reading section 201. The resulted data is JBIG compressed at the image compressing/expansion section 109 and is temporarily stored in a spool area 204 on the HDD 104. The monochrome MFP usually has resolution of 600 dpi or 1200 dpi and read image data is considered as 8 bit signals. The gamma processing section 202 corrects the image so that the print has the same density as the manuscript by considering device characteristic of the scanner 111 and a device characteristic of the printer 112. Then, the binary processing section 203 performs binary processing to output the image to the printer 112.
Binary image data is spooled here so that operation of each of a copy function, a scanner function, a document storage function, a facsimile function and a print function does not intervene the other functions when the functions are executed simultaneously. That enables copy operation to be performed during a waiting time of printing operation.
A processing flow until compression/expansion and spooling of image data is the same as above. Operation of each function starts from expanding the spooled compressed image data.
In copy operation, image data expanded at the image compression/expansion section 109 is sent as it is to the printer 112 to be outputted by the printer output section 206. With a scanner function, the expanded image data is converted into a data format which can be easily treated by the PC at a format converting section 205 and sent over a network via a network I/F 106 at a network transmitting section 207.
With a document storing function, spooled image data is stored as document data as it is in another area 208 of the HDD 104. The stored document data can be retrieved and reprinted or sent over a network in response to a user's instruction. In such a case, the image data stored in the spool area 204 is returned and the operation which is the same as the above-mentioned functions is performed.
As document data to be stored is spooled compressed image data, the document data is advantageous in that it can be reprinted or sent easily.
A processing flow of the color MFP will be described with reference to FIG. 2B.
The color MFP is different from the monochrome MFP in that the signals read and obtained by the scanner 111 are color signals. The color scanner usually has resolution around 600 dpi in consideration of the size of image data. The color scanner reads by 8 bits signals for each color of RGB.
The image data read at a scanner reading section 211 is converted from color spaces depending on a scanner device into standard color spaces at a scanner color processing section 212 that is mounted on the image processing section 108. That can be done only by processing such as well-known masking processing or three dimension look up table interpolation.
The 8-bit image data for each color of RGB after color conversion at the scanner color processing section 212 is JPEG compressed at the image compression/expansion section 109 and spooled in a spool area 213 as in the case of monochrome MFP.
The color MFP converts image data expanded at the image compression/expression section 109 from RGB to CMYK at a printer color processing section 214 mounted on the image processing section 108 in copy operation. After subjected to gamma correction at a gamma correction section 215 which includes calibration of tone characteristic of the printer, the image data is converted into half-tone image data with the number of bits (for example, two bits) which can be treated by the printer at a screen processing section 216 and sent to the printer 112 and outputted from a printer output 218.
With a scanner function, expanded image data is converted in format at a format converting section 217 as in the case of the monochrome MFP and sent over a network at a network transmitting section 219.
For a document storing function, image data of the spool area 213 is stored in a document storing area 220 as document data as in the monochrome MFP. Document data stored by the document storing function is reused in the same operation as in the monochrome MFP.
If a document on storage media such as a sheet of paper or the like is converted into electronic image data and stored in an MFP with a storage function mentioned above, a manuscript on sheets of paper can be obtained by reprinting and/or the manuscript can be delivered by image data with the storage function mentioned above.
<Grid Computing Technique>
On the other hand, parallel distributed processing computing techniques including the PC clustering technique or the grid computing technique have been developed.
The grid computing technique is a technique for facilitating a client on a network to equivalently access various resources of each processing node placed on a network, i.e., calculation resources in a CPU or memory, or storage resources such as an HDD.
[Patent Document 1] Japanese Patent Laid-Open No. 2003-099299
[Patent Document 2] National Publication of International Patent Application No. 2003-524836